Semiconductor device, display device, and method of manufacturing the same

ABSTRACT

In order to eliminate the disconnection of a pixel electrode caused by a change in shape of an interlayer insulating film at the ends of metal wiring, a resin film is formed at the ends of the metal wiring. Because of the resin film at the ends of the metal wiring, the step difference of the ends of the metal wiring is alleviated, and even if the interlayer insulating film is changed in shape, the ends of the metal wiring is prevented from peeling, whereby the disconnection of the pixel electrode can be prevented. Furthermore, the resin film flattens the surface of the interlayer insulating film, and prevents an alignment defect of liquid crystal molecules and a non-uniform electric field, thereby suppressing a minute defect of a light-emitting device caused by the roughness of the surface of the pixel electrode.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor device having acircuit composed of thin film transistors (hereinafter referred to asTFTs), a display device such as a light emitting device and a liquidcrystal display device, and a manufacturing method of the same.Specifically, the present invention relates to the technique of pixelelectrode periphery portion structures.

[0003] 2. Description of the Related Art

[0004] A technique for manufacturing a TFT from a semiconductor thinfilm (with a thickness of between several hundreds to several thousandsof nm) formed on a substrate having an insulating surface has recentlybeen developed. In particular, since a TFT in which a polysilicon film(polycrystalline silicon film) is an active layer (hereinafter referredto as polysilicon TFT) has high electric field effect mobility, the thinfilm transistor is widely applied to semiconductor devices such asintegrated circuits (hereinafter referred to as ICs) or electro-opticaldevices, and is needed to be developed promptly as, in particular, aswitching element for a display device or the like.

[0005] For example, in a semiconductor device, a pixel portion forperforming image displays on respective functional blocks, and anintegrated circuit for controlling the pixel portion, (such as a shiftregister circuit, a level shifter circuit, a buffer circuit, or asampling circuit which are based on a CMOS circuit) are formed on asingle substrate.

[0006] Further, active-matrix liquid crystal display devices arefrequently used as semiconductor devices because images with higherdefinition can be obtained compared to passive liquid crystal displaydevices. Also, the active-matrix liquid crystal display device includes:a gate wiring; a source wiring; a TFT in a pixel portion, which isprovided at the cross point of the gate wiring and the source wiring;and a pixel electrode connected to the TFT in the pixel portion.

[0007]FIG. 8 is a cross section diagram of the pixel portion of aconventional semiconductor device. As in FIG. 8 in a conventionalsemiconductor device, a pixel electrode 804 was directly connected to ametal wiring 802 connecting a pixel TFT 805 and a metal wiring 803connecting a storage capacitor 806.

[0008] However, an interlayer insulating film 801 contracts due to heat,and expands by containing water. Therefore, the following is confirmed:the wiring 802, 803 is likely to peel off the interlayer insulating film801 to cause a shape defect of the wiring 802, 803; and the pixelelectrode 804 is disconnected at a step portion of the wiring 802, 803.

[0009]FIG. 10 shows the above-mentioned defect of a wiring shape. FIG.10 shows an image obtained by an SIM (Scanning Ion Microscope) with amagnification of 27,500 times. A wiring (Ti/Al/Ti) and a pixel electrode(made of an indium oxide-tin oxide (In₂O₃—SnO₂) alloy (ITO)) areconnected to the surface of an interlayer insulating film (made ofacrylic resin). However, the wiring (Ti/Al/Ti) peels off the surface ofthe interlayer insulating film (acrylic resin). Along with this, thepixel electrode connected to the wiring (Ti/Al/Ti) is disconnected atthe ends of the wiring (Ti/Al/Ti).

[0010] Disconnection of the pixel electrode at the ends of the wiring(Ti/Al/Ti) is one of the causes for a point defect of a semiconductordevice.

[0011] There is also another problem. Due to the roughness of the uppersurface of the interlayer insulating film, the pixel electrode on theinterlayer insulating film is roughened to cause an alignment defect ofliquid crystal molecules and a non-uniform electric field.

[0012] Furthermore, due to the roughness of the upper surface of theinterlayer insulating film, the pixel electrode on the interlayerinsulating film is roughened to cause a defect of the light-emittingdevice in which a minute defect occurs in the light-emitting layerlaminated on the pixel electrode.

SUMMARY OF THE INVENTION

[0013] Therefore, with the foregoing in mind, it is an object of thepresent invention to provide a configuration for eliminatingdisconnection of pixel electrodes caused by a change in shape of aninterlayer insulating film at the ends of metal wiring and a method ofmanufacturing the same; and to enhance productivity, yield andreliability.

[0014] It is another object of the present invention to provide aconfiguration for preventing an alignment defect of liquid crystalmolecules and a non-uniform electric field caused by the roughness ofthe upper surface of an interlayer insulating film, and to enhanceproductivity, yield and reliability.

[0015] It is still another object of the present invention to provide aconfiguration for preventing a defect of a light-emitting device inwhich a minute defect occurs in a light-emitting layer due to theroughness of a pixel electrode caused by the roughness of the uppersurface of an interlayer insulating film and a method of manufacturingthe same, and to enhance productivity, yield, and reliability.

[0016] According to the present invention, by using an insulating film(typically a resin film), the processes of formation of a semiconductorlayer to formation of a pixel electrode are conducted with 6 photomaskswithout increasing the number thereof, and disconnection of the pixelelectrode is eliminated, whereby productivity, yield and reliability areenhanced.

[0017] Six photomasks include the following: a first photomask forforming a semiconductor layer; a second photomask for forming a gateelectrode; a third photomask for forming a semiconductor layercontaining an impurity element of one conductivity (n-type or p-type); afourth photomask for forming a contact hole; a fifth photomask forforming metal wiring; and a sixth photomask for forming a pixelelectrode.

[0018] Furthermore, according to the present invention, an insulatingfilm (typically resin film) is formed on an interlayer insulating filmso as to alleviate the step difference of ends of metal wiring. Morespecifically, an angle of the step difference of the ends of the metalwiring at which a pixel electrode extends is made gentle.

[0019] The resin film is formed so as to alleviate the step differenceof the ends of the metal wiring, so that the pixel electrode can beprevented from peeling off a portion with the step difference. Thus,productivity, yield, and reliability can be enhanced.

[0020] Furthermore, the resin film flattens the roughness of the uppersurface of the interlayer insulating film.

[0021] The resin film flattens the roughness of the surface of theinterlayer insulating film. Therefore, an alignment defect of liquidcrystal molecules and a non-uniform electric field, caused by theroughness of the upper surface of the interlayer insulating film, can beprevented, which enhances the productivity, yield, and reliability of asemiconductor device.

[0022] Furthermore, the resin film flattens the roughness of the uppersurface of the interlayer insulating film. Therefore, a defect of alight-emitting device, in which a minute defect of a light-emittinglayer occurs due to the roughness of a pixel electrode caused by theroughness of the upper surface of the interlayer insulating film, can beprevented. This enhances the productivity, yield, and reliability of alight-emitting device.

[0023] These and other advantages of the present invention will becomeapparent to those skilled in the art upon reading and understanding thefollowing detailed description with reference to the accompanyingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the accompanying drawings:

[0025]FIG. 1 is a cross-sectional view of a semiconductor display devicein which the present invention is carried out;

[0026]FIGS. 2A to 2C show processes of manufacturing the semiconductordisplay device;

[0027]FIGS. 3A to 3C show processes of manufacturing the semiconductordisplay device;

[0028]FIGS. 4A to 4C show processes of manufacturing the semiconductordisplay device;

[0029]FIGS. 5A to 5C show processes of manufacturing the semiconductordisplay device;

[0030]FIGS. 6A to 6C show processes of manufacturing the semiconductordisplay device;

[0031]FIGS. 7A to 7B show processes of manufacturing the semiconductordisplay device;

[0032]FIG. 8 is a cross-sectional view of a conventional semiconductordevice;

[0033]FIG. 9 shows a wiring shape in which the present invention iscarried out;

[0034]FIG. 10 shows a wiring defect in the conventional semiconductordevice;

[0035]FIGS. 11A and 11B show processes of manufacturing a light-emittingdevice;

[0036]FIG. 12 is a circuit configuration of an entire semiconductordisplay device;

[0037]FIGS. 13A to 13F illustrate examples of devices utilizing thesemiconductor display device;

[0038]FIGS. 14A and 14B illustrate examples of devices utilizing thesemiconductor display device; and

[0039]FIGS. 15A to 15D are cross-sectional views of the semiconductordisplay device in which the present invention is carried out.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] [Embodiment Mode 1]

[0041]FIG. 1 shows a semiconductor device of the present invention.According to the present invention, in order to eliminate thedisconnection of a pixel electrode 12 caused by a change in shape of aninterlayer insulating film 10 at the ends of metal wiring, an insulatingfilm (typically a resin film) 11 is formed on the interlayer insulatingfilm 10. Specifically, the insulating film 11 is formed in a sideportion of the metal wiring 13 and 14, which is interposed between theentire surface or a partial surface of the interlayer insulating film 10and the pixel electrode 12 and has a curved surface at a portion(sidewall portion of the metal wiring) in contact with the metal wiring13, 14, whereby the step difference of the ends of the metal wiring 13,14 is alleviated. Thus, even if the interlayer insulating film 10 ischanged in shape, the ends of the metal wiring 13, 14 are prevented frompeeling, whereby the disconnection of the pixel electrode 12 can beprevented.

[0042] Furthermore, because of the resin film 11, the roughness of theupper surface of the interlayer insulating film 10 can be flattened,which can flatten the surface of the pixel electrode 12. Therefore, analignment defect of liquid crystal molecules and a non-uniform electricfield can be prevented.

[0043] Herein, the insulating film (resin film in the present embodimentmode) 11 is made of a resin having a concentration lower than that ofthe interlayer insulating film 10 and having a decreased viscosity.Examples of the material for the resin film include polyimide, acrylicresin, polyamide, polyimideamide, BCB (benzocyclobutene), cyclobutene,and the like. Resin insulating films and organic SiO compounds otherthan those described above can also be used. An insulating film made ofan inorganic material can also be used as long as the flatness is high.

[0044] Furthermore, the insulating film 11 may be made of a materialdifferent from that of the interlayer insulating film 10, and anycombination of the above-mentioned materials may be used.

[0045]FIG. 9 shows a wiring shape in which the present invention iscarried out. FIG. 9 is an image obtained by an SIM (Scanning IonMicroscope) with a magnification of 19,000 times. A wiring (Ti/Al/Ti)and a pixel electrode (made of an indium oxide-tin oxide (In₂O₃—SnO₂)alloy (ITO)) are connected to the surface of an interlayer insulatingfilm (made of acrylic resin). According to the present invention, thewiring (Ti/Al/Ti) is connected to the surface of the interlayerinsulating film (acrylic resin) without peeling off. Therefore, a pixelelectrode connected to the wiring (Ti/Al/Ti) can be prevented from beingdisconnected at the ends of the wiring (Ti/Al/Ti).

[0046] Furthermore, the upper surface of the interlayer insulating filmcan be flattened according to the present invention. Therefore, thepixel electrode formed on the interlayer insulating film is alsoflattened, whereby an alignment defect of liquid crystal molecules and anon-uniform electric field can be prevented.

[0047] Furthermore, if the present invention is carried out in alight-emitting device, the upper surface of the interlayer insulatingfilm can be flattened, and the pixel electrode formed on the interlayerinsulating film can also be flattened. Therefore, a minute defect of thelight-emitting device caused by the roughness of the upper surface ofthe pixel electrode can be suppressed, which contributes to theenhancement of yield.

[0048] [Embodiment Mode 2]

[0049] Embodiment Mode 2 will be described with reference to FIGS. 15Ato 15D. In Embodiment Mode 2, the shape of an insulating film (typicallya resin film) formed so as to alleviate the step difference between theinterlayer insulating film and the ends of metal wiring, described inEmbodiment Mode 1, will be described. In FIGS. 15A to 15D, descriptionwill be made by using the same reference numerals as those in FIG. 1used for description in Embodiment Mode 1.

[0050]FIG. 15A is a view showing the semiconductor device in FIG. 1, andFIGS. 15B to 15D are enlarged views illustrating an interlayerinsulating film 10, metal wiring 13, 14, insulating films 11 b to 11 d(resin films are used in the present embodiment) that alleviate the stepdifference between the metal wiring and the interlayer insulating film,and a pixel electrode 12.

[0051] In FIG. 15B, the resin film 11 b covers the side surface of themetal wiring 13 or 14 and a part of the surface of the interlayerinsulating film 10, and has a curved surface. More specifically, theresin film 11 b is in contact with the side surface of the metal wiring13 or 14, the interlayer insulating film 10, and the pixel electrode 12,and has a curved surface in a side surface region of the metal wiring.In the case of such a shape, the step difference between the metalwiring 13, 14 and the interlayer insulating film 10 is alleviated.Therefore, the disconnection of the pixel electrode can be prevented,which contributes to the enhancement of yield. Furthermore, since theinterlayer insulating film 10 is in contact with the pixel electrode 12,there is no problem of interference fringes caused by the difference inmaterial between the interlayer insulating film 10 and the resin film 11b, and the range of selection of each material is large.

[0052] In FIG. 15C, the resin film 11 c covers a side surface region ofthe metal wiring 13, 14 and the surface of the interlayer insulatingfilm 10, and has a curved surface. More specifically, the resin film 11Cis in contact with the side surface region of the metal wiring 13, 14,the surface of the interlayer insulating film 10, and the pixelelectrode 12 and has a curved surface in the side surface region of thepixel electrode 12. In the case of such a shape, since the stepdifference between the metal wiring 13, 14 and the interlayer insulatingfilm 10 is alleviated, the disconnection of the pixel electrode 12 canbe prevented, which contributes to the enhancement of yield. If thematerial of the interlayer insulating film 10 is different from that ofthe resin film 11 d, interference fringes are formed to cause anirregular display. Therefore, in this case, it is desirable to minimizethe thickness of the resin film to be formed on the surface of theinterlayer insulating film.

[0053] In FIG. 15D, the resin film 11 d has substantially the samethickness as that of the metal wiring 13, 14. More specifically, theresin film 11 d is in contact with the side surface of the metal wiring13, 14, the interlayer insulating film 10, and the pixel electrode 12,and has a curved surface in a side surface region of the pixel electrode12 and substantially the same thickness as that of the metal wiring. Inthe case of such a shape, there is almost no step difference between themetal wiring 13, 14 and the interlayer insulating film 10. Therefore,the pixel electrode can be flattened, and a minute defect in alight-emitting device caused by the roughness of the upper surface ofthe pixel electrode can be suppressed, which contributes to theenhancement of yield. If the material of the interlayer insulating film10 is different from that of the resin film 11 d, interference fringesare formed to cause an irregular display. Therefore, it is desirable touse the same material.

[0054] Embodiments

[0055] [Embodiment 1]

[0056] A method of manufacturing a semiconductor device adopting thepresent invention will be described with reference to FIGS. 2A-7B andFIG. 12.

[0057] First, FIG. 12 shows a circuit configuration of the entiresemiconductor device adopting the present invention. The semiconductordisplay device is composed of a pixel region 1301, a gate signal linedriving circuit 1312, and a source signal line driving circuit 1313. Thegate signal line driving circuit 1312 includes a shift register circuit1306, a level shifter circuit 1307, a buffer circuit 1308, a firstprotection circuit 1311, and a second protection circuit 1309. Thesource signal line driving circuit 1313 includes a shift registercircuit 1302, a level shifter circuit 1303, a buffer circuit 1304, asampling circuit 1305, and a precharge circuit 1310.

[0058] A method of manufacturing a semiconductor device with theabove-described circuit configuration will be described specificallywith reference to FIGS. 2A-7B.

[0059] First, a semiconductor display device is manufactured by using asubstrate 100 with transparency. Examples of the substrate to be usedinclude glass substrates made of barium borosilicate glass,aluminoborosilicate glass, and the like, such as #7059 glass and #1737glass produced by Corning Inc. In addition, transparent substrates suchas a quartz glass substrate and a plastic substrate can also be used.

[0060] Then, a base film 101 made of an insulating film such as asilicon oxide film, a silicon nitride film, or a silicon oxynitride filmis formed on the substrate 100. For example, a silicon oxynitride filmformed of SiH₄, NH₃, and N₂ 0 by plasma CVD is formed to a thickness of10 to 200 nm (preferably 50 to 100 nm). Furthermore, hydrogenatedsilicon oxynitride film formed of SiN₄ and N₂ 0 is laminated on thesilicon oxynitride film to a thickness of 50 to 200 nm (preferably 10 to150 nm). In the present embodiment, the base film 101 has a two-layerstructure. However, the base film 101 may be a single-layer film of theinsulating film or a layered film including at least two layers.

[0061] Then, an amorphous semiconductor film 102 is formed on the basefilm 101 to a thickness of 25 to 80 nm (preferably 30 to 60 nm).Thereafter, a crystalline semiconductor film 103 is formed by lasercrystallization and known thermal crystallization. Although there is noparticular limit to the material for the crystalline semiconductor film103, it is preferable that the crystalline semiconductor film 103 may beformed of silicon or a silicon-germanium (SiGe) alloy.

[0062] In order to form the crystalline semiconductor film 103 by lasercrystallization, an excimer laser of a pulse oscillation type or acontinuous light-emitting type, a YAG laser, or a YVO₄ laser is used. Inthe case of using these lasers, laser light emitted from a laseroscillator is condensed in a line shape by an optical system so as to beirradiated to the semiconductor film. The condition for crystallizationis as follows. In the case of using an excimer laser, a pulseoscillation frequency is set at several 30 Hz, and a laser energydensity is set at 100 to 400 mJ/cm² (typically 200 to 300 mJ/cm²).Furthermore, in the case of using a YAG laser, the second harmonicthereof is used to set a pulse oscillation frequency at several 1 to 10kHz, and a laser energy density is set at 300 to 600 mJ/cm² (typically350 to 500 mJ/cm²). Laser light condensed in a line shape with a widthof 100 to 1000 μm (e.g., 400 μm) is irradiated over the entire surfaceof the substrate with an overlap ratio of the line-shaped laser lightbeing 80 to 98%.

[0063] After a silicon oxide film 105 is formed on the crystallinesemiconductor film 103, doping of an impurity element (boron orphosphorus) is conducted so as to control the threshold value of TFTs.Doping is conducted at a typical dose amount of 5×10¹³ atoms/cm² and anacceleration voltage of 30 kV.

[0064] Next, as shown in FIGS. 3A to 3C, semiconductor layers 202 to 206are formed using a resist 201 by first photolithography and etching.

[0065] Then, a gate insulating film 301 is formed so as to cover thesemiconductor layers 202 to 206. The gate insulating film 301 is formedof an insulating film containing silicon to a thickness of 40 to 150 nmby plasma CVD or sputtering. In the present embodiment, a siliconoxynitride film with a thickness of 120 nm is formed. Needless to say,the gate insulating film is not limited to such a silicon oxynitridefilm, and a single-layer or multi-layer structure of an insulating filmcontaining other silicon may be used. For example, in the case where asilicon oxide film is used, TEOS (tetraethyl orthosilicate) and O₂ aremixed by plasma CVD, and discharge is conducted at a reaction voltage of40 Pa, a substrate temperature of 300° C. to 400° C., and ahigh-frequency (13.56 MHz) power density of 0.5 to 0.8 W/cm², wherebythe gate insulating film can be formed. The silicon oxide film thusformed exhibits satisfactory characteristics as the gate insulating filmby thermal annealing at 400° C. to 500° C.

[0066] Next, in order to form a gate electrode on the gate insulatingfilm 301, a first conductive film 302 and a second conductive film 303are formed. In the present embodiment, the first conductive film 302 isformed of TaN to a thickness of 50 to 100 nm, and the second conductivefilm 303 is formed of W to a thickness of 100 to 300 nm.

[0067] In the present embodiment, the first conductive film 302 is madeof TaN, and the second conductive film 303 is made of W. However, thesefilms may be formed of an element selected from the group consisting ofTa, W, Ti, Mo, Al and Cu, an alloy material mainly containing theelement, or a compound material. Furthermore, a semiconductor film suchas a polycrystalline silicon film doped with an impurity element such asphosphorus may be used. Examples of the combination other than that ofthe present embodiment include a combination of the first conductivefilm made of tantalum (Ta) and the second conductive film made oftungsten(W), a combination of the first conductive film made of tantalumnitride (TaN) and the second conductive film made of aluminum (Al), anda combination of the first conductive film made of tantalum nitride(TaN) and the second conductive film made of copper (Cu).

[0068] Next, a resist mask is formed by second photolithography, andgate electrodes and wirings 304 to 308 are formed by first etching. Inthe present embodiment, the gate electrodes and wirings are formed byICP (Inductively Coupled Plasma) etching, in which etching gas is mixedand an RF power of 500 W is supplied to a coil-type electrode under apressure of 1 Pa to generate plasma. An RF power of 100 W is alsosupplied to the substrate (sample stage) side to apply a substantiallynegative self-bias voltage thereto. By appropriately selecting etchinggas, the W film and the TaN film are etched to the same degree.

[0069] Under the above-described etching condition, by making the shapeof a resist mask appropriate, the angles of taper portions at the endsof the first conductive film and the second conductive film become 15°to 45° due to the effect of a bias voltage applied to the substrateside. In order to etch the first and second conductive films withoutleaving a residue on the gate insulating film 301, an etching time maybe increased in a ratio of about 10 to 20%. Since the selection ratio ofthe silicon oxynitride film to the W film is 2 to 4 (typically 3), thesurface of which the silicon oxynitride film is exposed is etched byabout 20 to 50 nm by overetching. Thus, the gate electrodes and wiringsmade of the first conductive film and the second conductive film areformed by second photolithography.

[0070] Next, first doping is conducted, whereby an n-type impurityelement is added. Doping is conducted by ion doping or ion implantation.Ion doping is conducted at a dose amount of 1×10¹³ to 5×10¹⁴ atoms/cm²and an acceleration voltage of 60 to 100 keV. As an n-type impurityelement, an element belonging to Group 15 (typically phosphorus (P) orarsenic (As)) is used. Herein, phosphorus (P) is used. In this case, theconductive film functions as a mask with respect to the n-type impurityelement, and first impurity regions 314 to 323 are formed in aself-alignment manner. The n-type impurity element is added to the firstimpurity regions 314 to 323 in a concentration of 1×10²⁰ to 1×10²¹atoms/cm³.

[0071] Next, as shown in FIG. 4B, second etching is conducted. Reactivegas is introduced into a chamber, and a predetermined RF power issupplied to a coil-type electrode, whereby plasma is generated. Arelatively low RF power is supplied to the substrate (sample stage)side, and an auto-bias voltage lower than that of the first etching issupplied. The W film is subjected to anisotropic etching to obtainconductive films 309 to 313 with a second shape.

[0072] Furthermore, as shown in FIG. 4C, second doping is conducted. Inthis case, doping of an n-type impurity element is conducted under thecondition of a dose amount lower than that of the first doping and ahigher acceleration voltage. For example, doping is conducted at a doseamount of 1×10¹³ atoms/cm² and an acceleration voltage of 70 to 120 keV,whereby two kinds of impurity regions 401 to 422 are formed on an innerside of the first impurity regions 314 to 323 formed in thesemiconductor layer in FIG. 4C. Doping is conducted using the conductivefilm with a second shape as a mask with respect to an impurity elementin such a manner that the impurity element is also added to a regionunder the first conductive film. Thus, third impurity regions 402, 403,406, 407, 410, 411, 414, 415, 418, 419, and 422 are formed so as to beoverlapped with the first conductive film. The third impurity regions402, 403, 406, 407, 410, 411, 414, 415, 418, 419, and 422 have animpurity concentration lower than that of the second impurity regions401, 404, 405, 408, 409, 412, 413, 416, 417, 420, and 421, and theconcentration of the n-type impurity element is set at 1×10¹⁷ to 1×10¹⁸atoms/cm³ in the third impurity regions.

[0073] Next, third photolithography is conducted. Fourth impurityregions 426, 427, and 428 with a conductivity opposite to oneconductivity are formed in the semiconductor layers on which p-channelTFTs are to be formed. Using the conductive film with the second shapeas a mask with respect to an impurity element, impurity regions areformed in a self-alignment manner. At this time, the semiconductorlayers on which n-channel TFTs are to be formed are covered with resistmasks 423, 424, and 425. In the impurity regions, phosphorus is added inrespectively different concentrations. The impurity regions are dopedwith diborane (B₂H₆) by ion doping so that an impurity concentrationbecomes 2×10²⁰ to 2×10²¹ atoms/cm³.

[0074] As a result of the above-described processes, impurity regionsare formed in each semiconductor layer. The conductive layers overlappedwith the semiconductor layers function as gate electrodes of TFTs.

[0075] Then, as shown in FIG. 5C, the impurity elements added to eachsemiconductor layer are activated so as to control the conductivity.This process is conducted by thermal annealing using an annealingfurnace. Alternatively, laser annealing or rapid thermal annealing (RTA)can be used. According to thermal annealing, the impurity elements areactivated in a nitrogen atmosphere with a concentration of oxygen of 1ppm or less, preferably 0.1 ppm or less at 400° C. to 700° C., typically500° C. to 600° C. In the present embodiment, heat treatment isconducted at 500° C. for 4 hours. In the case where a wiring material isweak to heat, it is preferable that activation is conducted after aninterlayer insulating film (mainly containing silicon) is formed so asto protect the wirings and the like.

[0076] As shown in FIG. 5C, the first interlayer insulating film 501 isformed of a silicon oxynitride film to a thickness of 100 to 200 nm.Furthermore, a second interlayer insulating film 502 made of an organicinsulating material is formed on the first interlayer insulating film501. Examples of the material for the second interlayer insulating film502 include polyimide, acrylic resin, polyamide, polyimideamide, BCB,and the like. In the present embodiment, acrylic resin is used as amaterial for the second interlayer insulating film 502, and thethickness thereof is 1.6 μm.

[0077] Next, contact holes are formed by fourth photolithography.Contact holes are opened by dry etching. First, the second interlayerinsulating film 502 is etched, and thereafter, the first interlayerinsulating film 501 is etched.

[0078] Then, fifth photolithography is conducted. In a driving circuitportion, source wirings 503, 505, and 507 forming contact with sourceregions of the semiconductor layers and drain wirings 504, 506, and 508forming contact with drain regions are formed. In a pixel portion, asource wiring 509 and a drain electrode 511 are formed. In the presentembodiment, as metal wiring, Ti/Al/Ti is used.

[0079] Next, as shown in FIG. 6C, in order to prevent the stepdifference defect of pixel electrodes due to the shape defect of contactstep difference, an organic resin film 601 is formed as shown in FIG.6C. Polyimide, acrylic resin, polyamide, polyimideamide, BCB and thelike can be used for the organic resin film 601. The same material asthat for the second interlayer insulating film 502 can be used for theorganic resin film 601. In this case, the material with a concentrationand a viscosity lower than those of the second interlayer insulatingfilm 502 is used for the organic resin film 601. Typically, acrylicresin with a concentration of 3 to 20%, preferably 5 to 10% of that ofthe second interlayer insulating film may be used. In the presentembodiment, acrylic resin with a concentration of 10% of that of thesecond interlayer insulating film 502 is used.

[0080] The organic resin film 601 is formed by dropping an organic resinonto the substrate and applying thereto with a spin coater at a rotationnumber of 100 rpm to 2000 rpm (preferably 1000 rpm to 1500 rpm). In thepresent embodiment, 5 cc of acrylic resin with a dilution of 10 timesthat of the concentration of acrylic resin used for the secondinterlayer insulating film is dropped onto the substrate and appliedthereto at a rotation number of a spin coater of 1400 rpm. The rotationnumber may not be constant at all time. Organic resin can also beapplied at a low rotation number (100 rpm to 500 rpm) and then at a highrotation number (1000 rpm to 1500 rpm).

[0081] Next, the applied organic resin film 601 is baked by heattreatment at 250° C. for one hour.

[0082] Next, as shown in FIG. 7A, etching is conducted so as to removethe organic resin present on the wirings. In the present embodiment, ICPetching is conducted, in which etching gas is mixed, and an RF power of450 W is supplied to a coil-type electrode under a pressure of 1.2 Pa,whereby plasma is generated. An RF power of 100 W is also supplied tothe substrate (sample stage) side, and a substantially negativeself-bias voltage is applied. By appropriately selecting etching gas,the organic resin on the wirings is etched and removed.

[0083] In the present embodiment, ICP etching is used for the purpose ofremoving the organic resin on the wirings. The organic resin on thewirings can also be removed by ashing. For example, etching is conductedby supplying an RF power of 100 W to electrodes under a pressure of 67Pa to generate plasma. As etching gas, O₂ is mainly used.

[0084] Next, as shown in FIG. 7B, sixth photolithography is conducted,whereby a transparent pixel electrode 602 is formed on the organic resinfilm 601 for preventing the step difference defect of pixel electrodesdue to the shape defect of contact step difference. The transparentpixel electrode 602 can be formed of indium oxide (In₂O₃), an indiumoxide-tin oxide (In₂O₃—SnO₂: ITO) alloy, or the like by sputtering,vacuum vapor deposition, and the like. Such a material is etched with asolution of a hydrochloric acid type. However, a residue is likely to begenerated particularly by etching of ITO. Therefore, in order to improveprocessability of etching, indium oxide-zinc oxide In₂O₃—ZnO alloy maybe used. Zinc oxide (ZnO) is also a suitable material. Furthermore, zincoxide with gallium (Ga) added thereto (ZnO: Ga) or the like can be usedso as to enhance transmittance of visible light and conductivity.

[0085] As described above, in 6 photography processes, a driving circuitportion having n-channel TFTs, p-channel TFTs, and n-channel TFTs and apixel portion having pixel TFTs and storage capacitors can bemanufactured on the same substrate. As a result, the processes can beshortened, which can contribute to the reduction in manufacturing costand the enhancement of yield.

[0086] [Embodiment 2]

[0087] The present invention can also be carried out in a display device(hereinafter, referred to as a light-emitting device) using alight-emitting material that allows EL (electroluminescence) to beobtained. Hereinafter, a detailed method of manufacturing alight-emitting device adopting the present invention will be describedwith reference to FIGS. 11A and 11B. The processes prior to forming thesecond interlayer insulating film are the same as those in Embodiment 1.Therefore, the description thereof will be omitted here.

[0088] First, contact holes are formed in the first interlayerinsulating film and the second interlayer insulating film byphotolithography. The contact holes are opened by dry etching. Thesecond interlayer insulating film is etched, and thereafter, the firstinterlayer insulating film is etched.

[0089] Then, wirings are formed by photolithography. In a drivingcircuit portion, source wirings for forming contact with source regionsof the semiconductor layers and drain wirings for forming contact withthe drain regions are formed. In a pixel portion, source wirings anddrain wirings are formed. In the present embodiment, Ti/Al/Ti is usedfor metal wiring.

[0090] Next, in order to flatten the surface of the second interlayerinsulating film roughened by etching of wiring and the like, an organicresin film 1201 is applied to the surface of the second interlayerinsulating film. The same material as that for the second interlayerinsulating film can be used as the material for the organic resin film1201. More specifically, polyimide, acrylic resin, polyamide,polyimideamide, BCB, or the like can be used. Furthermore, the materialwith a concentration and a viscosity lower than those of the secondinterlayer insulating film is used for the organic resin film 1201.Preferably, acrylic resin with a concentration of 3 to 20%, preferably 5to 10% of that of the second interlayer insulating film may be used. Inthe present embodiment, acrylic resin with a concentration of 10% ofthat of the second interlayer insulating film is used.

[0091] The organic resin film 1201 is formed by dropping an organicresin onto the substrate and applying thereto with a spin coater at arotation number of 100 rpm to 2000 rpm (preferably 500 rpm to 1000 rpm).In the present embodiment, 5 cc of acrylic resin with a dilution of 10times that of the concentration of acrylic resin used for the secondinterlayer insulating film is dropped onto the substrate and appliedthereto at a rotation number of a spin coater of 1400 rpm. The rotationnumber may not be constant at all times. Organic resin can also beapplied at a low rotation number (100 rpm to 500 rpm) and then at a highrotation number (1000 rpm to 1500 rpm).

[0092] Next, the applied organic resin film 1201 is baked by heattreatment at 250° C. for one hour.

[0093] Next, etching is conducted so as to remove the organic resinpresent on the wirings. In the present embodiment, ICP etching isconducted, in which etching gas is mixed, and an RF power of 450 W issupplied to a coil-type electrode under a pressure of 1.2 Pa, wherebyplasma is generated. An RF power of 100 W is also supplied to thesubstrate (sample stage) side, and a substantially negative self-biasvoltage is applied. By appropriately selecting etching gas, the organicresin on the wirings is etched and removed.

[0094] In the present embodiment, ICP etching is used for the purpose ofremoving the organic resin on the wirings. The organic resin on thewirings can also be removed by ashing. For example, etching is conductedby supplying an RF power of 100 W to electrodes under a pressure of 67Pa to generate plasma. As etching gas, O₂ is mainly used.

[0095] Next, a transparent pixel electrode 1202 is formed on the organicresin film 1201 for flattening the roughness of the surface of thesecond interlayer insulating film. The transparent pixel electrode 1202can be formed of indium oxide (In₂O₃), an indium oxide-tin oxide(In₂O₃—SnO₂: ITO) alloy, or the like by sputtering, vacuum vapordeposition, and the like. Such a material is etched with a solution of ahydrochloric acid type. However, a residue is likely to be generatedparticularly by etching of ITO. Therefore, in order to improveprocessability of etching, indium oxide-zinc oxide (In₂O₃—ZnO) alloy maybe used. Zinc oxide (ZnO) is also a suitable material. Furthermore, zincoxide with gallium (Ga) added thereto (ZnO: Ga) or the like can be usedso as to enhance transmittance of visible light and conductivity.

[0096] Then, a bank 1203 is formed as shown in FIG. 11B. The bank 1203can be formed by patterning an insulating film or an organic resin filmcontaining silicon with a thickness of 100 to 400 nm. The bank 1203 isformed so as to fill a region between pixels (pixel electrodes). Thebank 1203 is formed also for the purpose of preventing an organic ELmaterial of a light-emitting layer and the like to be formed from cominginto contact with the ends of the pixel electrodes.

[0097] As the material for the bank 1203, photosensitive polyimide,photosensitive acrylic resin, non-photosensitive acrylic resin, or thelike can be used.

[0098] The bank 1203 is formed of an insulating film, so that careshould be taken so as not to cause electrostatic breakdown of a deviceduring film formation. In the present embodiment, carbon particles andpigment are added to the insulating film to be a material for the bankso as to decrease a resistance, whereby static electricity can besuppressed. In this case, the added amount of carbon particles andpigment should be adjusted so as to obtain a resistance value of 1×10⁶to 1×10¹² Ωm (preferably 1×10⁸ to 1×10¹⁰ Ωm).

[0099] Next, the surface of the bank is subjected to pre-treatment. Inthe present embodiment, the entire substrate is heated to 100° C. to120° C. and irradiated with UV-light while oxygen plasma is beingformed. Because of this, ozone plasma treatment is conducted withrespect to the surface of a positive electrode. Because of thepre-treatment, adsorbed oxygen and adsorbed water is removed on thesurface of the positive electrode, whereby a work function of thesurface is enhanced. Furthermore, the flatness of the surface of thepositive electrode is enhanced. The flatness of the surface of thepositive electrode should be set so that an average square roughness(RmS) is 5 nm or less (preferably 3 nm or less).

[0100] Instead of ozone plasma treatment, plasma treatment using raregas such as argon, neon, or helium may be conducted.

[0101] Next, an EL layer 1204 is formed by spin coating. In the presentembodiment, a lamination of a hole-injection layer and a light-emittinglayer is referred to as an EL layer. More specifically, a laminationobtained by combining a light-emitting layer with a hole-injectionlayer, a hole-transport layer, a hole-blocking layer, anelectron-transport layer, an electron-injection layer, or anelectron-blocking layer is referred to as an EL layer. The El layer maybe formed of an organic material or an inorganic material. Furthermore,the EL layer may be formed of a polymer material or a low-molecularmaterial.

[0102] In the present embodiment, first, polythiophene (PEDOT) is formedto a thickness of 20 nm as a hole-injection layer, andpolyvinylcarbazole (PVK) is formed to a thickness of 80 nm as alight-emitting layer emitting white light. Polythiophene is applied bybeing dissolved in water. Polyvinylcarbazole may be applied by beingdissolved in 1,2-dichloromethane. Furthermore, the hole-injection layerand the light-emitting layer are heat-treated in a temperature range(typically 80° C. to 120° C.) that does not break down the EL layer tovolatilize a solvent, whereby a thin film is obtained.

[0103] For example, PVK,Bu-PBD(2-(4′-tert-butylphenyl)-5-(4″-biphenyl)-1,3,4-oxadiazole),coumarin6, DCM1(4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran),TPB(tetraphenylbutadiene) and Nile Red dissolved in 1,2-dichloromethanecan be used.

[0104] Furthermore, as the polymer material used for the light-emittinglayer emitting white light, those which are described in Japanese PatentApplication Laid-Open No. 08-96959 or 09-63770 can also be used.

[0105] After the EL layer is formed, a cathode 1205 made of a conductivefilm with a small work function is formed to a thickness of 400 nm. Inthe present embodiment, the cathode 1205 is obtained by forming aluminumand lithium into an alloy by codeposition. Thus, an EL element includingthe pixel electrode (positive electrode) 1202, the EL layer 1204, andthe cathode 1205 is formed.

[0106] Next, a passivation film 1206 is formed so as to cover the ELelement completely after the cathode 1205 is formed. At this time, it ispreferable to use a film with good step coverage as the passivationfilm. It is effective to use a carbon film, in particular, a DLC(diamond like carbon) film. The DLC film can be formed in a range ofroom temperature to 100° C. Therefore, the DLC film can be formed easilyabove the EL layer with low heat resistance. Furthermore, the DLC filmcan suppress oxidation of the EL layer and the cathode due to its highblocking effect with respect to oxygen.

[0107] Furthermore, a sealing member 1207 is provided on the passivationfilm and a cover member 1208 is attached thereto. As the sealing member1207, a UV-curable resin may be used, and a material having amoisture-absorbing effect or an antioxidant effect can be provided inthe sealing member 1207.

[0108] As the cover member 1208, a glass substrate, a metal substrate, aceramics substrate, or a plastic substrate (including a plastic film)can be used. It is effective to provide a carbon film (in particular,DLC film) on both sides or one side of the cover member 1208. In thecase of using a plastic film as the cover member 1208, the DLC film canbe formed on both sides thereof by roll-to-roll method.

[0109] Thus, the state shown in FIG. 11B is obtained. It is effective toconduct the processes from formation of the bank 1203 to formation ofthe passivation film 1206 continuously without being exposed to theatmosphere by using a film-formation apparatus of a multi-chamber system(or an in-line system). When the EL layer 1204 is formed by spincoating, it is conducted in a nitrogen atmosphere or a rare gasatmosphere subjected to deoxidation.

[0110] As described above, by applying the organic resin film 1201 onthe second interlayer insulating film, the surface of the secondinterlayer insulating film can be flattened. Because of this, theflatness of the pixel electrode 1202 formed on the second interlayerinsulating film is enhanced, and a minute defect in the light-emittingdevice can be suppressed, which contributes to the enhancement of yield.

[0111] [Embodiment 3]

[0112] An active matrix substrate, and a liquid crystal display devicefabricated by carrying out the present invention can be used for variouselectro-optical devices. Further, the present invention can be appliedto all electronic equipments incorporating such electro-optical devicesas display media.

[0113] As the electronic instrument, a video camera, a digital camera, aprojector (rear or front type), a head mount display (goggle typedisplay), a navigation system, a personal computer, a portableinformation terminal (mobile computer, cellular telephone, electronicbook, etc.), and the like can be enumerated. Examples of these are shownin FIGS. 13 and 14.

[0114]FIG. 13A shows a personal computer which is comprised by a mainbody 1401, an image input portion 1402, a display portion 1403, and akeyboard 1404. The present invention can be applied to the image inputportion 1402, the display portion 1403 and other driving circuits.

[0115]FIG. 13B shows a video camera which is comprised by a main body1405, a display portion 1406, an audio input portion 1407, an operationswitch 1408, a battery 1409, and an image receiving portion 1410. Thepresent invention can be applied to the display portion 1406, the audioinput portion, and other driving circuits.

[0116]FIG. 13C shows a mobile computer which is comprised by a main body1411, a camera portion 1412, an image receiving portion 1413, anoperation switch 1414, and a display portion 1415. The present inventioncan be applied to the display portion 1415 and the other drivingcircuits.

[0117]FIG. 13D shows a goggle type display which is comprised by a mainbody 1416, a display portion 1417, and an arm portion 1418. The presentinvention can be applied to the display portion 1417 and other drivingcircuits.

[0118]FIG. 13E shows a player using a recording medium records a program(hereinafter referred to as a “recording medium”), which is comprised bya main body 1419, a display portion 1420, a speaker portion 1421, arecording medium 1422, and an operation switch 1423. This device uses aDVD (Digital Versatile Disc), CD, or the like for the recording medium,and can perform music appreciation, film appreciation, games and the usefor Internet. The present invention can be applied to the displayportion 1420 and the other driving circuits.

[0119]FIG. 13F shows a digital camera which is comprised by a main body1424, a display portion 1425, a viewfinder 1426, an operation switch1427, and an image receiving portion (not shown). The present inventioncan be applied to the display portion 1425 and the other drivingcircuits.

[0120]FIG. 14A shows a front type projector which is comprised by anoptical source system and a display device, and a screen 1502. Thepresent invention can be applied to the display device and the otherdriving circuits.

[0121]FIG. 14B shows a rear type projector which is comprised by a mainbody 1503, an optical source system and display device, a mirror 1505,and a screen 1506. The present invention can be applied to the displaydevice and the other driving circuits.

[0122] As described above, the applicable range of the present inventionis extremely wide, and the invention can be applied to electronicequipments in all fields. Note that the electronic equipments of thepresent embodiment can be achieved by utilizing any combination ofcomposition in Embodiments 1 to 3.

[0123] According to the present invention, TFTs are produced by using 6photomasks, and a resin film is formed at the ends of metal wiring,whereby pixel electrodes can be prevented from being disconnected due toa change in shape of an interlayer insulating film at the ends of themetal wiring. Furthermore, an alignment defect of liquid crystalmolecules and a non-uniform electric field, caused by the roughness ofthe surface of the interlayer insulating film, can be prevented.Furthermore, a defect of a light-emitting device, in which a minutedefect of a light-emitting layer occurs due to the roughness of thesurface of the pixel electrode, can be prevented. Thus, the productivityand yield of the semiconductor device and the light-emitting device canbe enhanced.

[0124] Various other modifications will be apparent to and can bereadily made by those skilled in the art without departing from thescope and spirit of this invention. Accordingly, it is not intended thatthe scope of the claims appended hereto be limited to the description asset forth herein, but rather that the claims be broadly construed.

What is claimed is:
 1. A semiconductor device comprising: a thin filmtransistor over a substrate; an insulating film covering the thin filmtransistor; a metal wiring on the insulating film, wherein the metalwiring is electrically connected to the thin film transistor; a pixelelectrode over the insulating film, the pixel electrode is electricallyconnected to the metal wiring; and a resin film between the insulatingfilm and the pixel electrode for alleviating a step difference betweenan edge of the metal wiring and the insulating film.
 2. A semiconductordevice according to claim 1, wherein the resin film comprises one or aplurality of kinds of materials selected from the group consisting ofpolyimide, acrylic resin, polyamide, polyimideamide, andbenzocylobutene.
 3. A semiconductor device according to claim 1, whereinthe semiconductor device is at least one selected from the groupconsisting of a personal computer, a video camera, a mobile computer, agoggle-type display, a player using a recording medium, digital camera,and a projector.
 4. A semiconductor device comprising: a thin filmtransistor over a substrate; a capacitor element over the substrate; aninsulating film covering the thin film transistor and the capacitorelement; a first metal wiring on the insulating film, wherein the firstmetal wiring is electrically connected to the thin film transistor; asecond metal wiring on the insulating film, wherein the second metalwiring is electrically connected to the capacitor element; a pixelelectrode over the insulating film, wherein the pixel electrode iselectrically connected to the first metal wiring and the second metalwiring; and a resin film between the insulating film and the pixelelectrode for alleviating step differences between an edge of the firstmetal wiring and the insulating film and between an edge of the secondmetal wiring and the insulating film.
 5. A semiconductor deviceaccording to claim 4, wherein the resin film comprises one or aplurality of kinds of materials selected from the group consisting ofpolyimide, acrylic resin, polyamide, polyimideamide, andbenzocylobutene.
 6. A semiconductor device according to claim 4, whereinthe semiconductor device is at least one selected from the groupconsisting of a personal computer, a video camera, a mobile computer, agoggle-type display, a player using a recording medium, digital camera,and a projector.
 7. A semiconductor device comprising: a thin filmtransistor over a substrate; a first insulating film covering the thinfilm transistor; a metal wiring on the first insulating film, whereinthe metal wiring is electrically connected to the thin film transistor;a pixel electrode over the first insulating film, wherein the pixelelectrode is electrically connected to the metal wiring; and a secondinsulating film in contact with a sidewall portion of the metal wiring,wherein the second insulating film is interposed between the pixelelectrode and the first insulating film, and has a curved surface at thesidewall portion of the metal wiring.
 8. A semiconductor deviceaccording to claim 7, wherein the second insulating film comprises oneor a plurality of kinds of materials selected from the group consistingof polyimide, acrylic resin, polyamide, polyimideamide, andbenzocylobutene.
 9. A semiconductor device according to claim 7, whereina concentration of the second insulating film is 3 to 20% of that of thefirst insulating film.
 10. A semiconductor device according to claim 7,wherein the semiconductor device is at least one selected from the groupconsisting of a personal computer, a video camera, a mobile computer, agoggle-type display, a player using a recording medium, digital camera,and a projector.
 11. A semiconductor device comprising: a thin filmtransistor over a substrate; a capacitor element over the substrate; afirst insulating film covering the thin film transistor and thecapacitor element; a first metal wiring on the first insulating film,wherein the first metal wiring is electrically connected to the thinfilm transistor; a second metal wiring on the first insulating film,wherein the second metal wiring is electrically connected to thecapacitor element; a pixel electrode over the first insulating film,wherein the pixel electrode is electrically connected to the first metalwiring and the second metal wiring; and a second insulating film incontact with sidewall portions of the first metal wiring and the secondmetal wiring, wherein the second insulating film is interposed betweenthe first insulating film and the pixel electrode, and has curvedsurfaces at the sidewall portions of the first metal wiring and thesecond metal wiring.
 12. A semiconductor device according to claim 11,wherein the second insulating film comprises one or a plurality of kindsof materials selected from the group consisting of polyimide, acrylicresin, polyamide, polyimideamide, and benzocylobutene.
 13. Asemiconductor device according to claim 11, wherein a concentration ofthe second insulating film is 3 to 20% of that of the first insulatingfilm.
 14. A semiconductor device according to claim 11, wherein thesemiconductor device is at least one selected from the group consistingof a personal computer, a video camera, a mobile computer, a goggle-typedisplay, a player using a recording medium, digital camera, and aprojector.
 15. A light emitting device comprising: a thin filmtransistor over a substrate; an insulating film covering the thin filmtransistor; a metal wiring-on the insulating film, wherein the metalwiring is electrically connected to the thin film transistor; a pixelelectrode over the insulating film, the pixel electrode is electricallyconnected to the metal wiring; and a resin film between the insulatingfilm and the pixel electrode for alleviating a step difference betweenan edge of the metal wiring and the insulating film.
 16. A lightemitting device according to claim 15, wherein the resin film comprisesone or a plurality of kinds of materials selected from the groupconsisting of polyimide, acrylic resin, polyamide, polyimideamide, andbenzocylobutene.
 17. A light emitting device according to claim 15,wherein the light emitting device is incorporated in at least oneselected from the group consisting of a personal computer, a videocamera, a mobile computer, a goggle-type display, a player using arecording medium, digital camera, and a projector.
 18. A light emittingdevice comprising: a thin film transistor over a substrate; a capacitorelement over the substrate; an insulating film covering the thin filmtransistor and the capacitor element; a first metal wiring on theinsulating film, wherein the first metal wiring is electricallyconnected to the thin film transistor; a second metal wiring on theinsulating film, wherein the second metal wiring is electricallyconnected to the capacitor element; a pixel electrode over theinsulating film, wherein the pixel electrode is electrically connectedto the first metal wiring and the second metal wiring; and a resin filmbetween the insulating film and the pixel electrode for alleviating stepdifferences between an edge of the first metal wiring and the insulatingfilm and between an edge of the second metal wiring and the insulatingfilm.
 19. A light emitting device according to claim 18, wherein theresin film comprises one or a plurality of kinds of materials selectedfrom the group consisting of polyimide, acrylic resin, polyamide,polyimideamide, and benzocylobutene.
 20. A light emitting deviceaccording to claim 18, wherein the light emitting device is incorporatedin at least one selected from the group consisting of a personalcomputer, a video camera, a mobile computer, a goggle-type display, aplayer using a recording medium, digital camera, and a projector.
 21. Alight emitting device comprising: a thin film transistor over asubstrate; a first insulating film covering the thin film transistor; ametal wiring on the first insulating film, wherein the metal wiring iselectrically connected to the thin film transistor; a pixel electrodeover the first insulating film, wherein the pixel electrode iselectrically connected to the metal wiring; and a second insulating filmin contact with a sidewall portion of the metal wiring, wherein thesecond insulating film is interposed between the pixel electrode and thefirst insulating film, and has a curved surface at the sidewall portionof the metal wiring.
 22. A light emitting device according to claim 21,wherein the second insulating film comprises one or a plurality of kindsof materials selected from the group consisting of polyimide, acrylicresin, polyamide, polyimideamide, and benzocylobutene.
 23. A lightemitting device according to claim 21, wherein a concentration of thesecond insulating film is 3 to 20% of that of the first insulating film.24. A light emitting device according to claim 21, wherein the lightemitting device is incorporated in at least one selected from the groupconsisting of a personal computer, a video camera, a mobile computer, agoggle-type display, a player using a recording medium, digital camera,and a projector.
 25. A light emitting device comprising: a thin filmtransistor over a substrate; a capacitor element over the substrate; afirst insulating film covering the thin film transistor and thecapacitor element; a first metal wiring on the first insulating film,wherein the first metal wiring is electrically connected to the thinfilm transistor; a second metal wiring on the first insulating film,wherein the second metal wiring is electrically connected to thecapacitor element; a pixel electrode over the first insulating film,wherein the pixel electrode is electrically connected to the first metalwiring and the second metal wiring; and a second insulating film incontact with sidewall portions of the first metal wiring and the secondmetal wiring, wherein the second insulating film is interposed betweenthe first insulating film and the pixel electrode, and has curvedsurfaces at the sidewall portions of the first metal wiring and thesecond metal wiring.
 26. A light emitting device according to claim 25,wherein the second insulating film comprises one or a plurality of kindsof materials selected from the group consisting of polyimide, acrylicresin, polyamide, polyimideamide, and benzocylobutene.
 27. A lightemitting device according to claim 25, wherein a concentration of thesecond insulating film is 3 to 20% of that of the first insulating film.28. A light emitting device according to claim 25, wherein the lightemitting device is incorporated in at least one selected from the groupconsisting of a personal computer, a video camera, a mobile computer, agoggle-type display, a player using a recording medium, digital camera,and a projector.
 29. A method of manufacturing a semiconductor device,comprising: forming a thin film transistor over a substrate; forming afirst insulating film covering the thin film transistor; forming acontact hole by etching the first insulating film; forming a metalwiring on the first insulating film, wherein the metal wiring iselectrically connected to the thin film transistor; forming a secondinsulating film on the first insulating film and the metal wiring bycoating; etching the second insulating film on the metal wiring toexpose a surface of the metal wiring; and forming a pixel electrode onthe second insulating film, wherein the pixel electrode is in contactwith the metal wiring.
 30. A method of manufacturing a semiconductordevice according to claim 29, wherein the coating is performed byrotating the substrate at a rotation number of 100 to 2000 rpm.
 31. Amethod of manufacturing a semiconductor device according to claim 29,wherein the semiconductor device is at least one selected from the groupconsisting of a personal computer, a video camera, a mobile computer, agoggle-type display, a player using a recording medium, digital camera,and a projector.
 32. A method of manufacturing a semiconductor device,comprising: forming a thin film transistor and a capacitor element overa substrate; forming an insulating film covering the thin filmtransistor and the capacitor element; forming a contact hole by etchingthe insulating film; forming a first metal wiring and a second metalwiring on the insulating film, wherein the first metal wiring and thesecond metal wiring are electrically connected to the thin filmtransistor and the capacitor element, respectively; forming a secondinsulating film on the first insulating film, on the first metal wiringand on the second metal wiring by coating; etching the second insulatingfilm on the first metal wiring and the second metal wiring to expose asurface of the first metal wiring and the second metal wiring; andforming a pixel electrode on the second insulating film, wherein thepixel electrode is in contact with the first metal wiring and the secondmetal wiring.
 33. A method of manufacturing a semiconductor deviceaccording to claim 32, wherein the coating is performed by rotating thesubstrate at a rotation number of 100 to 2000 rpm.
 34. A method ofmanufacturing a semiconductor device according to claim 32, wherein thesemiconductor device is at least one selected from the group consistingof a personal computer, a video camera, a mobile computer, a goggle-typedisplay, a player using a recording medium, digital camera, and aprojector.
 35. A method of manufacturing a light emitting device,comprising: forming a thin film transistor and a capacitor element overa substrate; forming an insulating film covering the thin filmtransistor and the capacitor element; forming a contact hole by etchingthe insulating film; forming a first metal wiring and a second metalwiring on the insulating film, wherein the first metal wiring and thesecond metal wiring are electrically connected to the thin filmtransistor and the capacitor element, respectively; forming a secondinsulating film on the first insulating film, on the first metal wiringand on the second metal wiring by coating; etching the second insulatingfilm on the first metal wiring and the second metal wiring to expose asurface of the first metal wiring and the second metal wiring; andforming a pixel electrode on the second insulating film, wherein thepixel electrode is in contact with the first metal wiring and the secondmetal wiring.
 36. A method of manufacturing a light emitting deviceaccording to claim 35, wherein the coating is performed by rotating thesubstrate at a rotation number of 100 to 2000 rpm.
 37. A method ofmanufacturing a light emitting device according to claim 35, wherein thelight emitting device is incorporated in at least one selected from thegroup consisting of a personal computer, a video camera, a mobilecomputer, a goggle-type display, a player using a recording medium,digital camera, and a projector.